Hughes & Kettner Warp Factor

Hughes & Kettner Warp Factor

Hughes & Kettner Warp Factor

The first thing you notice about this pedal its the unusual round shape: there are other effects with the same shape (Dallas Arbiter Fuzz Face and Expandora , just to mention two), but no one is dark, heavy (700 g) and menacing as this one :)

In addition to the usual “gain” and “level” knobs, there are 2 more controls: a “warp” knob and a “sub” button.

The “warp” knob is actually a tone control, which doesn’t work in the usual way: to the left it boosts mids from 250 Hz to 1 kHz. When set to the right, it cuts mids at 500 kHz with a subtle boost at 3 kHz.

Hughes & Kettner Warp Factor - front

Hughes & Kettner Warp Factor - front

The “sub” button is a low-end boost at 90 Hz (!) and is recommended for use with a 4×12 cabinet as you can see on the manual and on the reverse of the box.

By the way, as you can see in the photos, the input and output jack are reversed: I mean that the input jack is positioned on the left side while the output jack is on the right side…pretty weird choice imho, since the standard is exactly the opposite.

Hughes & Kettner Warp Factor - back

Hughes & Kettner Warp Factor - back

This pedal needs a whopping 180 mA of 12 V current: forget about using batteries, however a 700 mA power supply is included.

This effect was included in H&K catalog for year 2006, but is now discontinued: my personal opinion is that the sound isn’t bad, but probably its quirks were enough to condemn it to a fast “phase-out”. At the moment they can be found second-hand at reasonable price.


Weight: 700 g

Max. current consumption: 180 mA

Power supply: 14 V~

Input sensitivity: -14 dB

Input impedance: 1 MOhm

Output level: +6 dB

Output impedance: 3 kOhm


Original manual and catalog from H&K site



Bixonic Expandora II – Exp 2001

Bixonic Expandora - Exp 2001

Bixonic Expandora - Exp 2001 (front side)

As far as I know, this pedal has gone through 3 main versions: the original (and much sought after) Expandora, the 2001 version in this page, and a “reissue” version, called 2000-R.

Moreover, I am reasonably sure that Bixonic is no more in business, so we’ll probably will not see a new version anytime soon.

The 1st version had only three knobs on the outside, and some internal dip-switches that required to open the box to change settings: definitely not “user friendly” imho. The second version has no dip-switches, but a fourth knob labeled “Drive”, while the third version is similar to the 1st but the dip-switches can be easily accessed on top of the unit. All the knobs on this version are red, (yes, that’s why you can ofter hear about a “red knobs version”) smaller, difficult to spot and not really comfortable to use: however I admit that you can’t really change settings by accident, and that’s a plus.

Another difference is this: both the 1st and 2000R have a standard footswitch, while the 2001 has a large pad as you can see in the above image. Under the pad you can find the battery compartment.

Bixonic Expandora - Exp 2001 - Right side

Bixonic Expandora - Exp 2001 - Right side

However, another difference which you can’t miss is the light coming from the LEDs under the “Expandora II” badge on the top while playing with the unit switched on: I am sure its not just related to the input level alone, but I can’t tell :) . You can easily see this, in the videos at the links below. On a schematic on GeoFex site (see links below) it seems that LEDs are used as part of a compressor circuit, but I hadn’t open my unit to check it out.

All the units can be powered by a standard Boss style PSU, using the plug on top, or a 9V battery.

Bixonic Expandora - Exp 2001 - back side

Bixonic Expandora - Exp 2001 - back side


The Expandora II – 2001 on YouTube

A nice shootout/comparison between 2001 and 2000R version on YouTube

A supposed schematic for the Expandora on GeoFex site, use the link : ‘Schematics and More’ on left menu


Boss FZ-3 Fuzz

FZ-3 Fuzz (Boss)

The FZ-3 is the 2nd fuzz in the line of compact Boss pedals (the first one is the FZ-2 Hyper Fuzz).

It has been sold from 1997 to 1999, however it seems to me that finding an used one is not a problem.

Right now Boss is selling the FZ-5, which is completely different and uses COSM technology for classic fuzz emulation. This last model does not emulate the FZ-2 or FZ-3, anyway :(

In Boss intentions, this pedal should have a classic ’60 sound, however I’m not sure if this can be considered true, since I don’t have any classic fuzz like the Maestro or Dallas Fuzzface available for comparison.

As you can see in the above photo, the controls are very simple, and this is a deliberate step back from the FZ-2, which had more controls.


A demo video on YouTube

Another video on YouTube

Schematics for both FZ2 and FZ3


Boss OC-3 Super Octave

OC-3 Super Octave (Boss)

The OC-3, available since 2003, is the successor to the Boss OC-2 Octaver, with several improvements which make it a very different beast from the OC-2, while mantaining compatibility with it.

It has two inputs, one for guitar and one for bass, and 4 control knobs. The first one, starting from left to right, is for the original instrument input level, while the second one is for the lower octave volume. The function for the third knob depends on the position of the fourth one, which is a three-position rotary switch.

In the first mode (called “Drive”) the third knob is for distortion level. It should be noted that when using “Drive” both the original and lower octave will be distorted if using “Output (mono)” jack, but only the lower octave sound will be distorted on “Direct Out” output jack.

In the second “OCT2″ mode, this control is for the 2nd lower octave level, just the same as in the OC-2 pedal.

In the third “POLY” mode, the control acts as a “Range” control: i.e. extends the range of frequencies on which the pedal applies its effect. This mode is also recommended if you are playing more than one note at a time.

OC-3 Super Octave (Boss) Box


Nominal Input Level: -20 dBu

Nominal Output Level: -20 dBu

Current Draw: 50 mA

Input Impedance: 1 MOhm

Output Impedance: 1 kOhm

Residual Noise Level: -96 dBu (IHF-A)

Recommended Load Impedance: 10 kOhm or greater

OC-3 Page on Boss USA site, with brochure and audio demo

OC-3 Page on Boss Japan site, with both video and audio demo and user’s manual

An OC-3 demo on YouTube

Demo video from BOSS on YouTube


Boss NF-1 Noise Gate

NF-1 Noise Gate (Boss)

This is a simple noise reduction unit, the first one in Boss compact pedals line-up, and can be used to get rid of background noise and hum during silent passges while playing.

It has been sold from 1979 to 1988, while right now the only compact noise-reduction system is the NS-2.

The NF-1 has two controls: Sens and Decay. Sens (for Sensitivity) sets the threshold for intervention, while Decay sets the intervention time after last signal, from 100 msec to 1.6 seconds.


- Input Impedance: 470 kOhm

- Recommended Load Impedance: 10 kOhm or higher

- Current Draw: 3.9 mA

Schematics for the NF-1 can be found here:

NF-1 Schematic (Free Info Society)

NF-1 Schematic (Schematic Heaven)


Behringer UC100 Ultra Chorus

UC100 Ultra Chorus (Behringer)

This has been, for some time, the least expensive stereo chorus stompbox you could buy here in Italy (and I’d bet that the same was true in a lot of other countries, too:) ).

Right now, the UC100 is not present anymore in Behringer price list, and I think the UC-200 may have replaced it. I’m a little uncomfortable talking about this effect: the reason is that it does what is supposed to, it is unbelievably inxepensive, and the sound is not as good as the other chorus pedals I’ve tested, it isn’t really bad either. However, this last point is subject to debate, since the price of the other units I’m talking about is *5* (yes, five) times higher… so, I’m not sure I can make a fair comparison.

Guitar players can spend impressive amounts of money to get the sound they want: for guitar stompboxes you usually have to pay a lot to get good stuff (sometimes you can spend a lot and get burned, anyway). For this reason, I will not talk further about the sound: however the construction is far from other more expensive products. The box is made of plastic, and considering the general structure, I wouldn’t kick around this unit on a stage. One thing I simply don’t like is the DC input on the right side, near the signal input: I’d have preferred DC input on top of the unit.

Another thing I’m not exactly happy about is the battery compartment: to replace the 9V battery you have to “press the hinges with a ballpen and remove the pedal cover”. Owww…. and the author of the manual adds “Be careful not to scratch the pedal”. Very funny. In the photo, you can notice some velcro-like stuff glued on the bottom of the box by the owner.

UC-100 on Behringer site

UC-100 on Youtube